1. Field of the Invention
The present invention is directed to systems, methods, and devices applicable to spinal surgery. More specifically, the present invention is directed to an interbody spacer for use by medical personnel (i.e., doctor) in spinal and other surgical procedures. Some embodiments of the present invention relate to an interbody spacer for insertion into a disk space defined between two adjacent vertebrae, in order to restore an appropriate height between the vertebrae and to allow bone fusion to take place between said adjacent vertebrae.
2. Background of the Invention
Vertebrae are the individual irregular bones that make up the spinal column (aka ischis)—a flexuous and flexible column. There are normally thirty-three vertebrae in humans, including the five that are fused to form the sacrum (the others are separated by intervertebral discs) and the four coccygeal bones which form the tailbone. The upper three regions comprise the remaining 24, and are grouped under the names cervical (7 vertebrae), thoracic (12 vertebrae) and lumbar (5 vertebrae), according to the regions they occupy. This number is sometimes increased by an additional vertebra in one region, or it may be diminished in one region, the deficiency often being supplied by an additional vertebra in another. The number of cervical vertebrae is, however, very rarely increased or diminished.
A typical vertebra consists of two essential parts: an anterior (front) segment, which is the vertebral body; and a posterior part—the vertebral (neural) arch—which encloses the vertebral foramen. The vertebral arch is formed by a pair of pedicles and a pair of laminae, and supports seven processes, four articular, two transverse, and one spinous, the latter also being known as the neural spine.
When the vertebrae are articulated with each other, the bodies form a strong pillar for the support of the head and trunk, and the vertebral foramina constitute a canal for the protection of the medulla spinalis (spinal cord), while between every pair of vertebrae are two apertures, the intervertebral foramina, one on either side, for the transmission of the spinal nerves and vessels.
Conventional interbody spacer assemblies are used in spinal fusion procedures to repair damaged or incorrectly articulating vertebrae. Conventional interbody spacer assemblies come in different cross sections. Some spacer assemblies may be hollow and may include openings in the side(s) thereof to provide access for bone matter growth.
Historically one of the failure modes of interbody spacers, designed to support and stabilize the anterior column of the spine, is one of migration. This has been previously addressed by incorporating features on the upper and lower surfaces of implants to resist migration. Some implant designs have integrated features that prevent the implant from migrating once installed but restrict the ease of implant insertion such as spikes and protrusions, creating a paradoxical relationship where implant manufacturers must choose between either making the implant easier to insert or making the implant less likely to migrate. Wedge features have been previously utilized to resist migration however have been limited in their application by preferentially resisting migration in limited directions, such as wedge designs that are only symmetric across the saggital plane.
There exists a need for further improvements in the field of interbody spacer assemblies of the present type.